Quantificação de DNA plasmático em pacientes com cancro da mama

• Author(s): Ferreira, Maria Manuel da Silva
• Date: 2011
• Persistent ID: http://hdl.handle.net/10216/22401
• Origin: Repositório Aberto da Universidade do Porto
• Subject(s): Oncologia Molecular; Porto
• Document Type: Master thesis
• Language: Portuguese

Description

Breast cancer is the leading cause of cancer death in women worldwide. The purpose of our study was to determine whether the amounts of circulating DNA could discriminate between breast cancer patients and healthy individuals by using real-time PCR based DNA quantification methodology and determine the kinetics of circulating plasma DNA in surgically treated patients. Our standard protocol for quantification of cell free plasma DNA involved 175 consecutive patients with breast cancer and 80 healthy controls. The quantification was perfomed by real-time PCR amplification of the human telomerase reverse transcriptase gene (hTERT). We found increased levels of circulating DNA in breast cancer patients compared to control individuals (105.2 vs 77.06 ng/ml, p<0.001). We also found statistically significant differences in circulating DNA amounts in patients before and after breast surgery (105.2 vs 59.0 ng/ml, p=0.001). Increased plasma cell free DNA concentration was a strong risk factor for the presence of breast cancer, conferring an increased risk for the development of this disease (OR, 12.32; 95% CI, 2.09 52.28; p<0.001). High levels of plasma DNA were also correlated with a decrease in patients overall survival. There were no association between clinicopathological parameters and concentrations of cell free circulating DNA. In conclusion, cell-free DNA is significantly increased in plasma of breast cancer patients, which is associated with an increased risk for the presence of this disease and decrease of patient s survival. Therefore, quantification of circulating DNA by real-time PCR may be a good and simple tool for early detection of breast cancer with potential to clinical applicability together with other current methods used for monitoring the disease.